AHRMA Racer
XS650 New Member
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Hello all!
New to the site and XS650's, but I have ridden dirt bikes since 1976. I thought I was a decent mechanic but my "new" XS650 has me confounded.
Here's the deal: 1983 Heritage Special, all stock and original 14,000 miles, fairly good shape. Sat for some time before I bought it.
Cleaned the carbs and put a new battery in it, did a general servicing. Started right up, idles great, excellent response with no hesitation, runs and rides just fine. I have ridden it about 300 miles with no other issues, aside from what I'll describe below. Great story, right?
Here is the problem: It doesn't want to rev over 4,000-4,500 RPM. The left bank misfires as if it is running rich, plug is slightly black. In fact, the day I did ride it on a 240 mile ride, I had my brother take it with me following. When it hits the 4,000-4,500 range it stumbles and puffs a little black smoke out the left exhaust and it smells like fuel, so I think it is a carburetor problem.
Here's another odd thing. You can whack the throttle wide open clear in the basement and it will run perfectly and pull had up to the 4,000 rpm point where it starts to stumble and miss, so it is not throttle position all the time.
Ignition? Iread that the TCI coils randomly fail and will cause symptioms like this, so I replaced it with a Mike's High output coil. ZERO effect.
Any clue or anyone have this issue before?
New to the site and XS650's, but I have ridden dirt bikes since 1976. I thought I was a decent mechanic but my "new" XS650 has me confounded.
Here's the deal: 1983 Heritage Special, all stock and original 14,000 miles, fairly good shape. Sat for some time before I bought it.
Cleaned the carbs and put a new battery in it, did a general servicing. Started right up, idles great, excellent response with no hesitation, runs and rides just fine. I have ridden it about 300 miles with no other issues, aside from what I'll describe below. Great story, right?
Here is the problem: It doesn't want to rev over 4,000-4,500 RPM. The left bank misfires as if it is running rich, plug is slightly black. In fact, the day I did ride it on a 240 mile ride, I had my brother take it with me following. When it hits the 4,000-4,500 range it stumbles and puffs a little black smoke out the left exhaust and it smells like fuel, so I think it is a carburetor problem.
Here's another odd thing. You can whack the throttle wide open clear in the basement and it will run perfectly and pull had up to the 4,000 rpm point where it starts to stumble and miss, so it is not throttle position all the time.
Ignition? Iread that the TCI coils randomly fail and will cause symptioms like this, so I replaced it with a Mike's High output coil. ZERO effect.
Any clue or anyone have this issue before?
